1. Technical Field
This invention relates generally to processing of optical fiber and, more particularly, to methods and apparatuses for guiding optical fibers or optical fiber ribbons under tension in a fiber optic ribbon or cable manufacturing process.
2. Related Art
Manufacturers of fiber optic ribbons or cables, have faced the problem of fiber breaks, and fiber coating and/or ribbon matrix damage during processing of the optical fibers. This breakage/damage is attributable to a number of activities conducted during the processing which generally includes the feeding of optical fiber together. For instance, see U.S. Pat. No. 4,720,165 to Tokuda, et al., incorporated herein by reference. As shown in Tokuda, et al., these processes oftentimes require the fiber(s) or ribbon(s) to be held in tension along their length and to be bent over a variety of guides such as rollers, roller sheaves, and/or stationary members.
One problem which causes fiber breaks, or matrix/coating damage (hereinafter "breakage/damage") is the bending radii of the length of material, i.e., fiber or ribbon, being chosen incorrectly. In particular, the bending radii being excessively small or large can be a problem. First, glass breakage can occur where a length of material is to be supported on a guide at a point or line, i.e., draped over the guide and not touching extensively. In this instance, the length of material bends too much where it passes over the guide because of an over demanding turn angle or excessive tension being applied to the length of material. Second, coating or matrix damage can occur when the turn angle or tension of the length of material is too small for the length of material to conform to the curvature of a guide which is meant to support the length of material on a surface so as to avoid point or line contact with the length of material.
In either problem creating scenario, engineers who create the equipment and processes oftentimes do not know the radii of curvature to which a fiber or ribbon is being exposed. Accordingly, if acceptable bend radii are provided, it is by happenstance. Unfortunately, unacceptable bend radii are also unknowingly incorporated into the set-up. As a further consequence, because the breakage/damage to the fiber may occur in many other ways, a problem created by incorrect bending may not be readily noticeable. Engineers therefore are unlikely to be able to ascertain that the breakage/damage problem is created by a bend radius issue.
For the above reasons, there exists a need for a method of intentional preparation for bending of the fiber or ribbon under tension during the manufacturing processes regardless of whether the problem arises when the length of material is supported on a guide surface or when a guide supports the length of material at a point or line. Further, there is a need for an apparatus which uses equipment that exhibits conformance with appropriate bend radii criteria while guiding a length of material under tension.